Fan

ABSTRACT

A fan is provided incorporating one or more fan blades adapted to move in a back-and-forth sweeping motion about a generally horizontal axis in order to generate air flow both laterally and vertically. Fan blades with large surface areas may be used to generate the desired volumes of air movement.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. Provisional Application No. 61/268,730, filed on Jun. 15, 2009, the contents of which are fully incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to electric ceiling fans, and more particularly, to a fan with a fan blade that moves in a back-and-forth sweeping motion about a generally horizontal axis.

Ceiling fans typically have a motor mounted within a housing that is suspended from a ceiling. A plurality of fan blades, typically made out of a rigid material such as wood or hard plastic, extend horizontally from the main housing and are attached to the motor's drive shaft which is oriented vertically. In operation, the motor rotates the blades in a continuous 360 degree rotation around the vertically-oriented motor drive shaft, which causes air to be drawn in a generally downward direction.

Although variations on the basic ceiling fan design have been developed, including blade shape designs, motor housing designs and covers, the basic design of a plurality of horizontally extending fan blades from a main housing and adapted to rotate about a substantially vertical axis has remained unchanged. Specifically, variations in fan blade design have been developed to provide greater downward airflow or greater lateral airflow than traditional designs. However, most of these designs include horizontally extending blades adapted to rotate about a substantially vertical axis.

Accordingly, it is seen that a need exists for an improved fan that moves relatively large amounts of air both laterally and vertically, and which does not require fast spinning blades rotating about a substantially vertical axis.

SUMMARY OF THE INVENTION

In accordance with the present invention, a fan is provided incorporating one or more fan blades adapted to move in a back-and-forth sweeping motion about a generally horizontal axis in order to generate air flow both laterally and vertically. Fan blades with large surface areas may be used to generate the desired volumes of air movement.

In one exemplary embodiment, a fan is provided having a motor, a drive wheel coupled to and rotatable by a motor drive shaft of the motor, at least one fan blade coupled to the drive wheel, wherein each fan blade is pivotable about a generally horizontal axis, and wherein the generally horizontal axis is offset from the rotational axis of the motor drive shaft. In another exemplary embodiment, the fan blade is flexible. In a further exemplary embodiment, the fan blade is flexible and contains a plurality of flexible stiffening rods. In yet another exemplary embodiment, the fan blade is flexible and trapezoidal-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade is flexible and rectangular-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade has a minimum surface area of approximately 4,500 square inches. In yet another exemplary embodiment, the fan blade is adapted to baffle sound. In another exemplary embodiment, one or more ceiling support members are connected to the motor. The ceiling support members may be hollow.

In another exemplary embodiment, a fan is provided having a motor, a drive wheel coupled to and rotatable by a motor drive shaft of the motor, wherein the drive wheel is coupled to the motor drive shaft about a first point, at least one fan blade coupled to the drive wheel by at least one drive rod pivotally connected to at least one bell crank, wherein the drive rod is connected to the drive wheel about a second point, the drive rod is connected to the bell crank about a third point, the bell crank is pivotally connected to an axle about a fourth point, each fan blade is pivotable about a generally horizontal axis, and wherein the generally horizontal axis is offset from the rotational axis of the motor drive shaft.

In a further exemplary embodiment, the radius of the drive wheel, as measured from the first point to the second point, is less than the length of the bell crank, as measured from the third point to the fourth point. In another exemplary embodiment, the fan blade is flexible. In a further exemplary embodiment, the fan blade is flexible and contains a plurality of flexible stiffening rods. In yet another exemplary embodiment, the fan blade is flexible and trapezoidal-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade is flexible and rectangular-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade has a minimum surface area of approximately 4,500 square inches. In yet another exemplary embodiment, the fan blade is adapted to baffle sound. In another exemplary embodiment, one or more ceiling support members are connected to the motor, wherein said ceiling support members are hollow.

In another exemplary embodiment, a method for cooling a room includes providing a fan having a fan blade, displacing at least 50,000 cubic feet of air per minute, consuming a maximum of approximately 50 watts of electricity, and wherein displacing the air comprises pivoting the fan blade about a generally horizontal axis, by an electric motor. In another exemplary embodiment, the fan blade is flexible. In a further exemplary embodiment, the fan blade is flexible and contains a plurality of flexible stiffening rods. In yet another exemplary embodiment, the fan blade is flexible and trapezoidal-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade is flexible and rectangular-shaped and contains a plurality of flexible stiffening rods and a plurality of sleeves housing the plurality of flexible stiffening rods. In another exemplary embodiment, the fan blade has a minimum surface area of approximately 4,500 square inches. In yet another exemplary embodiment, the fan blade is adapted to baffle sound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the fan according to a first exemplary embodiment showing a trapezoidal-shaped fan blade 21.

FIG. 2 is a perspective view of a portion of the fan according to a first exemplary embodiment.

FIG. 3 is a perspective view of the fan according to a second exemplary embodiment.

FIG. 4 is an exploded view of the parts employed in the first exemplary embodiment of the fan.

FIG. 5 is a view of a geared motor 30, a motor mount flange 25, five isolation bolts 26, 27, 28, 29, and 33, and a motor drive shaft 22.

FIG. 6 is a detail view of the motor mount flange 25, the drive shaft 22, and a rod end bearing journals 6, 18, 19, 20.

FIG. 7 is a perspective view of the fan according to a third exemplary embodiment.

FIG. 8 is a perspective view of the fan according to a fourth exemplary embodiment.

FIG. 9 is a detail view of a trapezoidal-shaped fan blade 21, a rod support terminal 13, two horizontal rods 31 and 32, and two rods 14 and 15.

DETAILED DESCRIPTION

With reference to FIGS. 1, 2, 4, 5, 6, and 9, a fan according to a first exemplary embodiment of the invention will first be described. In FIGS. 1, 2, 4, and 9, identical reference numerals are used for representing constituent elements of the fan of the first exemplary embodiment.

FIG. 1 is a perspective view showing the fan in the first exemplary embodiment. FIG. 1 shows a trapezoidal-shaped fan blade 21 formed from a flexible material, e.g., a fabric, and supported by two horizontal rods 31 and 32, and supported by two rods 14 and 15, oriented obliquely relative to a rod support terminal (13 in FIGS. 2 and 9). In other exemplary embodiments, the fan blade 21 may be formed from a rigid material, e.g., wood or metal. In the first exemplary embodiment, the two horizontal rods 31 and 32, and the two rods 14 and 15, are formed from a flexible material, e.g., plastic, wood, metal, or composite. The fan blade 21, especially if formed from a flexible material, may contain sleeves used to house the two horizontal rods 31 and 32, and the two rods, 14 and 15. The sleeves may be formed with the same material as the fan blade 21. The two horizontal rods 31 and 32, connected to and extending outward from the rod support terminal (13 in FIGS. 2 and 9) form a horizontal hanging support for the fan blade 21. The two rods 14 and 15, are attached to the rod support terminal (13 in FIGS. 2 and 9) and are slipped into the sleeves in the fan blade 21. FIG. 9 shows a detail view of the trapezoidal-shaped fan blade 21, the rod support terminal 13, the two horizontal rods 31 and 32, and the two rods 14 and 15, according to the first exemplary embodiment.

FIG. 2 is a perspective view showing a portion of the fan in the first exemplary embodiment. Shown in FIG. 2, a fan having a motor housing 3 is suspended from a ceiling by two ceiling support members 16 and 17. In other exemplary embodiments, one or more ceiling support members may be used. In the first exemplary embodiment, two fan hanger mounting flanges (34 and 35 in FIG. 4) are welded to the motor housing 3 and are adapted to receive and are connected to the two ceiling support members 16 and 17.

With continued reference to FIG. 2, in this exemplary embodiment, a 12-volt or 24-volt DC planetary geared motor (30 in FIG. 5), or other low voltage motor, is mounted within the motor housing 3 and connected to a power source by wires that extend through the fan hanger mounting flanges (34 and 35 in FIG. 4) and the two ceiling support members 16 and 17. A motor drive shaft (22 in FIGS. 2 and 5) attached to the geared motor (30 in FIG. 5) rotatably drives a drive wheel 2 in a 360-degree rotation cycle. In this exemplary embodiment, the motor mounting flange (25 in FIG. 5) is attached to a main support arm 1 with five (5) isolation bolts (26, 27, 28, 29, and 33 in FIGS. 5 and 6). Opposite sides of the motor housing 3 are connected to the main support arm 1 and a back plate (4 in FIG. 4), respectively.

As the drive wheel 2 rotates through the 360-degree rotation cycle it pushes and pulls a drive rod 7 which is pivotally connected to the drive wheel 2. The drive rod 7 is coupled to a second drive rod 8 by a bell crank 5 which is pivotally attached to the main support arm 1 by means of an axle 38 rotatably supported by a flanged ball bearing (39 in FIGS. 2 and 4) attached to the main support arm 1. As the first drive rod 7 is pushed and pulled by the rotating drive wheel 2, the first drive rod 7 pivotally drives the bell crank 5 which pushes and pulls the second drive rod 8 synchronously with the first drive rod 7. The first drive rod 7 and the second drive rod 8 are attached to opposite end portions of the bell crank 5. Opposite ends of the first drive rod 7 are connected to the bell crank 5 and the drive wheel 2 by two rod end bearing journals, 6 and 18, respectively. Opposite ends of the second drive rod 8 are connected to the bell crank 5 and the drive lever 12 by two rod end bearing journals, 19 and 20, respectively. In this exemplary embodiment, the radius of the drive wheel 2, as measured from the drive shaft 22 attachment point on the drive wheel 2 to the rod end bearing journal 18 attachment point on the drive wheel 2, is shorter than the length of the bell crank 5, as measured from the rod end bearing journal 6 attachment point on the bell crank 5 to the axle 38 attachment point on the bell crank 5, so as to cause the drive rod 7 to pivotally drive the bell crank 5 in a back-and-forth motion.

As the second drive rod 8 is pushed and pulled, the second drive rod 8 pivotally drives an axle drive lever 12 back-and-forth about a generally horizontal axis (40). The axle drive lever 12 is fixed to an axle 9 which is pivotable about the generally horizontal axis (40) and is supported by two flanged ball bearings, 23 and 37, which are attached to the back plate 4 and the main support arm 1, respectively. The axle 9 is connected to two axle arms, 10 and 11, and the two axle arms, 10 and 11, are connected to the rod support terminal 13. The axle 9, the two axle arms 10 and 11, and the rod support terminal 13 pivot back-and-forth about the generally horizontal axis (40) synchronously with the axle drive lever 12. The two axle arms, 10 and 11, fixed to the axle 9 and fixed to the rod support terminal 13 pivotally drive the fan blade 21 in a back-and-forth sweeping motion about the generally horizontal axis (40). The fan blade 21 is supported by the two horizontal rods, 31 and 32, extending outward from and connected to opposite ends of the rod support terminal 13 and is supported by the two rods, 14 and 15, oriented obliquely relative to the rod support terminal (13 in FIGS. 2 and 9).

Applicant has apprehended that this exemplary embodiment of the fan cools a room by providing an electric motor which consumes a maximum of approximately 50 watts of electricity while rotating a fan blade with a minimum surface area of approximately 4,500 square inches about a generally horizontal axis and displacing more than 50,000 cubic feet of air per minute, e.g., 55,000 cubic feet per minute. The applicant has also apprehended the large surface area of the fan blade in this exemplary embodiment acts as a sound baffle to mitigate echoes in large rooms.

FIG. 3 is a perspective view showing the fan in a second exemplary embodiment. FIG. 3 shows a fan which is essentially the same as the first exemplary embodiment described in reference to FIG. 2 except for the shape of the fan blade 36. FIG. 3 shows a rectangular-shaped fan blade 36 formed from a flexible material, e.g. a fabric, and supported by a horizontal rod (H) and seven (7) support rods (A), (B), (C), (D), (E), (F), and (G), oriented at approximately 90 degrees relative to the horizontal rod (H). In other exemplary embodiments, the fan blade 36 may be formed from a rigid material, e.g., wood or metal. In the second exemplary embodiment, the horizontal rod (H) and the seven support rods (A), (B), (C), (D), (E), (F), and (G), may be formed from a flexible material, e.g., plastic, wood, metal, or composite. The fan blade 36, especially if formed from a flexible material, may contain sleeves used to house the horizontal rod (H) and the seven support rods (A), (B), (C), (D), (E), (F), and (G). The sleeves may be formed with the same material as the fan blade 36.

With reference to FIGS. 4, 5, and 7, a third exemplary embodiment will be described. FIG. 7 is a perspective view showing the fan in the third exemplary embodiment. A fan having a motor housing 103 is suspended from a ceiling by two ceiling support members, 116 and 117. In other exemplary embodiments, one or more ceiling support members may be used. In the third exemplary embodiment, two fan hanger mounting flanges (34 and 35 in FIG. 4) are welded to the motor housing 103 and are adapted to receive and are attached to the two ceiling support members, 116 and 117.

A 12-volt or 24-volt DC planetary geared motor (30 in FIG. 5), or other low voltage motor, is mounted within the motor housing 103 and connected to a power source in the ceiling by wires that extend through the fan hanger mounting flanges (34 and 35 in FIG. 4) and the two ceiling support members, 116 and 117. A motor drive shaft 122 which is attached to the geared motor (30 in FIG. 5) rotatably drives a drive wheel 102 in a 360-degree rotation cycle. In this exemplary embodiment, a motor mounting flange (25 in FIG. 5) is attached to a first main support arm 101 with five (5) isolation bolts, (26, 27, 28, 29, and 33 in FIG. 5). Opposite sides of the motor housing 103 are connected to a first main support arm 101 and a second main support arm 114, respectively. As the drive wheel 102 rotates through the 360-degree rotation cycle it pushes and pulls a drive rod 107 pivotally connected to the drive wheel 102. Opposite ends of the drive rod 107 are pivotally connected to a bell crank 105 and the drive wheel 102 by rod end bearing journals, 106 and 118, respectively. As the drive rod 107 is pushed and pulled by the rotating drive wheel 102, the drive rod 107 pivotally drives the bell crank 105 in a back-and-forth motion about a generally horizontal axis (138). The bell crank 105 is fixed to an axle 109 which is pivotable about the generally horizontal axis (138) and is supported by two flanged ball bearings, 137 and 123, which are attached to the first main support arm 101 and the second main support arm 114, respectively. In this exemplary embodiment, the radius of the drive wheel 102, as measured from the drive shaft 122 attachment point on the drive wheel 102 to the rod end bearing journal 118 attachment point on the drive wheel 102, is shorter than the length of the bell crank 105, as measured from the rod end bearing journal 106 attachment point on the bell crank 105 to the axle 109 attachment point on the bell crank 105, so as to cause the drive rod 107 to pivotally drive the bell crank 105 in a back-and-forth motion about the generally horizontal axis (138).

With continued reference to FIG. 7, the axle 109 is connected to two axle arms, 110 and 111, and the two axle arms, 110 and 111, are connected to a rod support terminal 113. The axle 109, the two axle arms, 110 and 111, and the rod support terminal 113 all pivot back-and-forth about the generally horizontal axis (138) synchronously with the bell crank 105. The axle 109 is pivotally supported by two flanged ball bearings, 137 and 123, which are connected to the first main support arm 101 and the second main support arm 114, respectively. The axle 109, connected to the two axle arms, 110 and 111, and connected to the rod support terminal 113, pivotally drive a fan blade 121 formed from a flexible material, e.g., a fabric, in a back-and-forth sweeping motion about the generally horizontal axis (138). In other exemplary embodiments, the fan blade 121 may be formed from a rigid material, e.g., wood or metal. In the third exemplary embodiment, a set of two horizontal rods, 131 and 132, extending outward from and connected to opposite ends of the rod support terminal 113 form a horizontal hanging support for the fan blade 121. The two horizontal rods, 131 and 132, are formed from a flexible material, e.g., plastic, wood, metal, or composite. In other exemplary embodiments, one or more rods may be connected to the fan blade 121 and used to support the fan blade 121.

FIG. 8 is a perspective view showing the fan in a fourth exemplary embodiment. Here, the fan in the fourth exemplary embodiment is similar to the third exemplary embodiment described in reference to FIG. 7 except that the fan includes a second fan blade 247 opposite a first fan blade 221 and includes the support structure necessary to pivotally drive the second fan blade 247 in a back-and-forth sweeping motion. In the fourth exemplary embodiment, both the first fan blade 221 and the second fan blade 247 are formed from a flexible material, e.g., a fabric. In other exemplary embodiments, the first fan blade 221 and the second fan blade 247 may be formed from a rigid material, e.g., wood or metal. According to the fourth exemplary embodiment, FIG. 8 shows the support structure necessary to pivotally drive the second fan blade 247, which includes a third main support arm 240, a fourth main support arm 241, a second drive rod 208, a second bell crank 242, a second axle 243, a second rod support terminal 246, and a second set of two axle arms, 244 and 245. The support structure necessary to pivotally drive the second fan blade 247 in the fourth exemplary embodiment is oriented and connected in a manner similar to that described in the third exemplary embodiment. The assemblage of the structure necessary to rotatably drive the second fan blade 247 in the fourth exemplary embodiment is a mirror image of the structure shown in FIG. 7 in reference to the third exemplary embodiment.

With continued reference to FIG. 8, a fan having a motor housing 203 is suspended from a ceiling by two ceiling support members, 216 and 217. In other exemplary embodiments, one or more ceiling support members may be used. In the fourth exemplary embodiment, two fan hanger mounting flanges (34 and 35 in FIG. 4) are welded to the motor housing 203 and are adapted to receive and are attached to the two ceiling support members, 216 and 217. Opposite sides of the motor housing 203 are connected to a first and the third main support arm, 201 and 240, and a second and the fourth main support arm, 214 and 241, respectively.

In this exemplary embodiment, a 12-volt or 24-volt DC planetary geared motor (30 in FIG. 5), or other low voltage motor, is mounted within the motor housing 203 and connected to a power source by wires that extend through the fan hanger mounting flanges (34 and 35 in FIG. 4) and the two ceiling support members, 216 and 217. A motor drive shaft 222 which is attached to the geared motor (30 in FIG. 5) rotatably drives a drive wheel 202 in a 360-degree rotation cycle. The drive wheel 202 is connected to a first drive rod 207 and the second drive rod 208. As the drive wheel 202 rotates through the 360-degree rotation cycle it synchronously pushes and pulls the first drive rod 207 and the second drive rod 208. Opposite ends of the first drive rod 207 are pivotally connected to a first bell crank 205 and the drive wheel 202 by two rod end bearing journals, 206 and 218, respectively. As the first drive rod 207 is pushed and pulled by the rotating drive wheel 202, the first drive rod 207 pivotally drives the first bell crank 205 in a back-and-forth motion about a first generally horizontal axis (238). Opposite ends of the second drive rod 208 are pivotally connected to a second bell crank 242 and the drive wheel 202 by two rod end bearing journals, 220 and 219, respectively. As the second drive rod 208 is pushed and pulled by the rotating drive wheel 202, the second drive rod 208 pivotally drives the second bell crank 242 in a back-and-forth motion about a second generally horizontal axis (252).

The first bell crank 205 is connected to a first axle 209 which is pivotable about the first generally horizontal axis (238) and is supported by two flanged ball bearings, 237 and 223, which are connected to a first main support arm 201 and a second main support arm 214, respectively. The second bell crank 242 is connected to a second axle 243, which is rotatable about the second generally horizontal axis (252) and is supported by two flanged ball bearings, 251 and 250, which are connected to the third main support arm 240 and the fourth main support arm 241, respectively. In this exemplary embodiment, the radius of the drive wheel 202, as measured from the drive shaft 222 attachment point on the drive wheel 202 to the rod end bearing journal 218 attachment point on the drive wheel 202, is shorter than the length of the first bell crank 205, as measured from the rod end bearing journal 206 attachment point on the first bell crank 205 to the axle 209 attachment point on the first bell crank 205, and is shorter than the length of the second bell crank 242, as measured from the rod end bearing journal 220 attachment point on the second bell crank 242 to the axle 243 attachment point on the second bell crank 242, so as to cause the first drive rod 207 to pivotally drive the first bell crank 205 in a back-and-forth motion about the first generally horizontal axis 238 and so as to cause the second drive rod 208 to pivotally drive the second bell crank 242 in a back-and-forth motion about the second generally horizontal axis 252.

The first and second axle, 209 and 243, are connected to a first set of two axle arms, 210 and 211, and a second set of two axle arms, 244 and 245, respectively. The first set of two axle arms, 210 and 211, are connected to a first rod support terminal 213 and the second set of two axle arms, 244 and 245, are connected to a second rod support terminal 246. The first and second axle, 209 and 243, the first set of two axle arms, 210 and 211, the second set of two axle arms, 244 and 245, and the first and second rod support terminal, 213 and 246, all pivot synchronously with the rotation of the drive wheel 202.

The first set of two axle arms, 210 and 211, fixed to the first axle 209 and fixed to the first rod support terminal 213 pivotally drive the first fan blade 221 in a back-and-forth sweeping motion about the first generally horizontal axis (238). The second set of two axle arms, 244 and 245, fixed to the second axle 243 and fixed to the second rod support terminal 246 pivotally drive the second fan blade 247 in a back-and-forth sweeping motion about the second generally horizontal axis (252). The first and second fan blades 221 and 247 are supported by a first set of two horizontal rods, 231 and 232, and a second set of two horizontal rods, 248 and 249, respectively. The first set of two horizontal rods, 231 and 232, and the second set of two horizontal rods, 248 and 249, extend outward from and are connected to opposite ends of the first and second rod support terminals, 213 and 246, respectively. The first set of two horizontal rods, 231 and 232, and the second set of two horizontal rods, 248 and 248, are formed from a flexible material, e.g., plastic, wood, metal, or composite. In other exemplary embodiments, one or more rods may be connected to the first fan blade 221 and the second fan blade 247 and used to support the first fan blade 221 and the second fan blade 247.

While this invention has been described in detail with particular references to the exemplary embodiments thereof, it will be understood by those skilled in the art that variations, additions and deletions, are contemplated within the scope of this invention. The exemplary embodiments described herein are not intended to be exhaustive or to limit the scope of the invention to the exact forms disclosed. 

1. A fan comprising: a motor; a drive wheel coupled to and rotatable by a motor drive shaft of the motor; wherein the drive wheel is coupled to the motor drive shaft about a first point; at least one fan blade coupled to the drive wheel, wherein each fan blade is pivotable about a generally horizontal axis; and wherein the generally horizontal axis is offset from the rotational axis of the motor drive shaft.
 2. The fan of claim 1, wherein: the fan blade is coupled to the drive wheel by at least one drive rod pivotally connected to at least one bell crank; the drive rod is connected to the drive wheel about a second point; the drive rod is connected to the bell crank about a third point; and the bell crank is pivotally connected to an axle about a fourth point.
 3. The fan of claim 2, wherein: the radius of the drive wheel, as measured from the first point to the second point, is less than the length of the bell crank, as measured from the third point to the fourth point.
 4. The fan of claim 1, wherein: the fan blade is flexible.
 5. The fan of claim 5, wherein: the fan blade comprises a plurality of flexible stiffening rods.
 6. The fan of claim 5, wherein: the fan blade is trapezoidal-shaped and has a plurality of sleeves housing said rods.
 7. The fan of claim 5, wherein: the fan blade is rectangular-shaped and has a plurality of sleeves housing said rods.
 8. The fan of claim 1, wherein: the fan blade has a minimum surface area of approximately 4,500 square inches.
 9. The fan of claim 1, further comprising: one or more ceiling support members connected to the motor, wherein said ceiling support members are hollow.
 10. A method for cooling a room comprising: providing a fan having a fan blade; displacing at least 50,000 cubic feet of air per minute; consuming a maximum of approximately 50 watts of electricity; and wherein displacing the air comprises pivoting the fan blade about a generally horizontal axis, by an electric motor.
 11. The method of claim 10, wherein: the fan blade is flexible.
 12. The method of claim 11, wherein: the fan blade comprises a plurality of flexible stiffening rods.
 13. The method of claim 12, wherein: the fan blade is trapezoidal-shaped and has a plurality of sleeves housing said rods.
 14. The method of claim 12, wherein: the fan blade is rectangular-shaped and has a plurality of sleeves housing said rods.
 15. The method of claim 10, wherein: the fan blade has a minimum surface area of approximately 4,500 square inches.
 16. The method of claim 10, wherein: the fan blade is adapted to baffle sound. 